Modelling and Control of a New High Step-Up Current-Fed Converter for Photovoltaic Applications

The use of high step-up converters becomes necessary for photovoltaic applications, due to low voltage of photovoltaic (PV) modules. In this paper, an isolated dc-dc high step-up SEPIC (single ended primary inductor converter) with a Greinacher voltage doubler cell is proposed for this application. It has the advantage of continuous input current, high efficiency, high voltage gain, isolation and demands a single switch, being suitable for low power grid-tie photovoltaic systems. In order to present the modelling and control, the dynamic model of the converter is obtained using the state-space averaging technique. For the control strategy, a Proportional Controller (PI) is used with the Maximum Power Point Tracking (MPPT) to regulate the input voltage of the PV module. A simulation result is presented to validate the obtained model, while closed-loop experimental results on a 50 kHz, 310 W prototype are presented to validate the proposed concept.